Air control gate for oil burner and the like



Nov. 26, 1957 R. w. BECKETT AIR CONTROL GATE FOR OIL BURNER AND THE LIKEFiled Aug. 12, 1953 [N VEN TOR. PEG/Nam M BECKETT BY M/M A TTOQNE IUnited States Patent AIR CONTROL GATE FOR OIL BURNER AND THE LIKEReginald W. Beckett, Elyria, Ohio Application August 12, 1953, SerialNo. 373,819

11 Claims. (Cl. 230-114) This invention relates to fluid fuel burnersand more particularly to regulation and control of the air supply inburners incorporating a power driven blower or fan.

It has long been recognized that proper control of the air supply inburners for oil and other fluid fuels is of prime importance inobtaining optimum efficiency and desirable operating characteristics.Oil burners and the like employing motor driven fans and blowerscommonly include means such as gates, shutters and louvers for governingthe air flow.

In practice, a single model or design of oil burner may be used to burnoil or other fluid fuel at many different rates so that the rate atwhich air is supplied to support combustion may vary over a relativelywide range. Since it is not feasible to supply completely differentcomponents for each burner model and since individual burners of thesame model will vary as to air requirements because of nozzledifferences and the like, the provision for air control to obtaindifferent air supply rates without losing the fundamentalcharacteristics of the flowing air with respect to rotation andturbulence is an ever present problem in burner design and construction.This problem was encountered in the development of the socalled platemounted burner" of U. S. Patent 2,599,153 and of Serial No. 152,353,filed March 28, 1950, now Patent No. 2,777,509, and of United Statesapplication for patent, Serial No. 149,550, filed March 14, 1950, ofwhich application the present application is a continuation in part.United States application, Serial No. 149,550 is in turn a continuationin part of application, Serial No. 766,967, filed August 7, 1947, nowUnited States Patent 2,506,192, and of United States application, SerialNo. 24,559, filed May 1, 1948, now the previously referred to UnitedStates Patent No. 2,599,153.

Burners of the character referred to comprise an open faced housinghaving a main wall carrying outside and partition walls which define fanscroll and air receiving chambers and a passage connecting the chambersfor conducting air discharged tangentially from one chamber into theother. The open face of the housing is closed as by a suitable flatplate or as by being disposed against the upright wall of a heater. Theclosure plate or the heater wall is formed with openings registeringwith the housing chambers so that air may be drawn into the fan scrollchamber through one such opening. Because of the geometry of the burnerhousing, particularly because of its normally close-coupled relation tothe heater structure with which it is normally associated but alsobecause of the use of a separate plate for closing the open face of thehousing, conventional air control devices and arrangements are notwholly satisfactory and do not provide the desired range of oil rates,the desired air flow characteristics or turbulence. The presentinvention seeks to provide an improved combination of burner housing andair control gate, the combination being particularly useful in fluidfuel burners comprising open face housings.

According to one of its principal features the combination is embodiedin a burner housing having connected fan scroll and air receivingchambers and a movable control gate disposed in a connecting passagebetween the chambers, tne gate being so located as to intercept at leasta portion or the air discharged tangentially into the passage from amass of air rotating in the scroll chamber and to deflect suchlntercepted air into the central portion of the air receiving chamber.As a refinement of this aspect of the invention the control gate ispivoted on the housing to swing from a retracted position in which itsubstantially parallels the path of air flowing tangentially from thescroll chamber and tangentially into the receiving chamber to an airintercepting and deflecting position, the gate being movableprogressively across the flow path of the air so that air dischargedtangentially from the periphery of the fan chamber is influenced by thegate to flow at a reduced rate and into a more central part of thereceiving chamber. By this arrangement the normal tangential entrance ofthe air into the receiving chamber is reduced or varied as desiredsimultaneously with the reduction or variation in the flow rate.

In accordance with another aspect of the invention an air control gateis pivotally mounted to swing about an axis at or adjacent the outerperiphery of the fan chamber and the gate is suitably notched orapertured in the provision of an opening which in all positions ofadjustment of the control gate permits part of the outermost portion ofthe tangentially or peripherally discharged air to flow through thecontrol gate and thereby maintain a predetermined minimum tangentialflow of air into the receiving chamber, this being one of the objects ofthe invention.

Another aspect of the invention concerned with the piv otal mounting ofan air control gate to swing across the tangential passage connectingfan scroll and air receiving chambers contemplates the provision in oneof the walls, preferably the outer or tangential wall of the connectingpassage, of a recess to accommodate the air gate pivot and the end ofthe gate so that the air gate at least at the pivoted end is recessedinto the wall of the connecting passage in the provision of astreamlined air flow arrangement which avoids objectionable eddycurrents and turbulences in the transfer of air from the fan scrollchamber to the air receiving chamber.

A still further feature and objective is concerned with the mounting ofan air control gate in a burner housing of the open face type, theinvention contemplating the use of a pin mounted in a boss on the mainwall of the housing and projecting as a cantilever from such boss toreceive an air gate for swinging movement. As a refinement of thisaspect of the invention the pivot pin is journaled in the boss with theair gate secured on the pin so that turning of the pin, preferably bymeans secured on an externally projecting cantilever portion thereof,shifts the air gate to different positions of adjustment within thehousing.

Other objects and advantages pertain to certain novel features ofconstruction and combinations and arrangements of parts which contributeto the provision of a generally improved air control arrangement that issimple and inexpensive and can be readily assembled and adjusted. Thefeatures and objectives referred to and others not specificallymentioned above are apparent in the following detailed description of apreferred embodiment of the invention, this description being made inconnection with the accompanying drawings forming a part of thespecification.

In the drawings:

Figure l is an elevational view, partly in section and with parts brokenaway and removed, showing the hous ing of a plate mounted oil burnerhaving an air control system embodying the principles of the presentinvention, the flat cover plate or closure being removed from the openface of the housing to show the interior of the housing and certain ofthe components of the burner used in association with the housing;

Figure 2 is a fragmentary side elevational view of Fig. I. this viewshowing the housing and related parts and components as though takenalong the line indicated at 22 of Fig. 1 and enlarged with respect tothat figure:

Figure 3 is a fragmentary enlarged detail showing the swingable aircontrol gate and its location in the housing passage which connects thefan scroll chamber and the air receiving chamber of the burner;

Figure 4 is a fragmentary sectional detail through the housing showingthe mounting means for the gate, this view being taken substantiallyalong the line indicated at 44 of Fig. 3; and

Figure 5 is a fragmentary sectional detail through the boss formed onthe main Wall of the housing for journaling the pivot shaft of the aircontrol gate, this view being taken substantially along the lineindicated at 55 of Fig. 4.

Burners for oil or other fluid fuels of the type for which the aircontrol gate and system of the present invention is adapted may beeither free standing or plate mounted as desired, a burner havingconvertible features making it suitable for both types of applicationbeing described in copending application Serial No. 152,353. Since thein vention is concerned with the control of air flow through the passageconnecting the fan scroll chamber and the air receiving chamber of thehousing, the present drawings are directed principally to the housingand the air gate in the housing. reference being made to the earlierpatent application for more complete descriptions and illustrations oithe burner and the manner in which it is used.

Briefly described, the burner comprises an open face housing generallyovate in shape and including a substantially fiat main wall 1 on whichrelated burner com ponents are mounted. Extending laterally from themain wall 1 and substantially normal to the plane of the latter are anarcuately or semicylindrically curved top wall 2 and arcuately curvedlower side walls 3 and 4. Along opposite sides of the housing areupright walls 5 and 6 which connect the ends of the top wall 2 t theupper ends of the lower side walls 3 and 4, respectively. Like thecurved walls 2, 3 and 4. the side walls and 6 are normal to the plane ofthe main wall 1, and, as shown. may be integral therewith. The interiorof the housing is divided into a number of chambers or compartments bypartitions that are normal to the plane of the main wall and, like thetouter or marginal Walls 26. may be integral with the main wall.

In the top of the housing an upper arcuately curved partition 7 definesa blower or fan chamber 8 and in the lower part of the housing anarcuately curved partition defines an air receiving chamber 10. Theinner ends of the partitions 7 and 9 are connected by an uprightpartition 11 spaced from the curved lower side wall 3 and the uprightstraight side wall 5 to define a passage 12 which connects the upper fanchamber to the lower air receiving chamber. The upper end of the fanchamber partition 7 is curved into or joins tangentially with the curvedtop wall 2 of the housing to provide a relatively smooth continuous peripheral wall for the fan chamber 8 from a cutoff point 14 where thecurved partition 7 joins the upright connecting partition 11 to adischarge point 15 at the entering end of a connecting passage 12. Thepartition 9 which defines the air receiving chamber II] is joinedtangentially to the lower side wall 3 or, as shown, may comprise asmoothly curved continuation of the latter so that air may flowsubstantially tangentially from the connecting passage 12 into thereceiving chamber 10 to rotate in the latter and form a spirally movingbody which continuously advances axially from the receiving chamber intoand through an air tube 16 which defines a passage that extends as acontinua tion of the chamber.

In a heater-burner combination the burner is secured in spaced relationto upright wall 17 of the heater by a cantilever type mountingarrangement. The open face of the burner housing is covered by a closureplate 20 which constitutes a wall panel of the burner housing. This fiatplate is interposed between the housing and the base of the air tube 16,being formed with an opening 22 which registers with the air receivingchamber 10 in the housing and with the passage through the air tube. Theclosure plate is also formed with a circular aperture 21 concentric tothe axis of a sirocco type blower or fan which is rotatably mounted inthe fan chamber 8, the aperture 21 constituting the inlet through whichair enters the fan chamber.

An electric motor 23 is flange mounted as by screws 24 against the mainwall 1 of the housing, the motor having a shaft 25 which extends intothe air chamber 8 through an opening 26 in the main wall I. The fan 19is secured on the shaft 25 so as to be driven by the motor 23 and tothereby force air tangentially from the scroll chamber 3 through theconnecting passage 12 and into the air rcceiving chamber 10. As shown inFig. l, the fan E9 is eccen trically located with respect to thepartition 7 and the top wall 2, the circular periphery of the fan beingclosest to the chamber defining walls at or adjacent the cutoff point14. There is thus defined between the circular fan periphery and thewalls 2 and 7 an arcuately curved chamber portion which progressivelyincreases in cross sectional area in the direction of fan rotation(indicated by the arrow) substantially from the cutotf point 14 to thedischarge point 15.

To locate and support the burner on the upright wall 17 of the heater,studs 28 are welded to spaced points of the outside face of the plate orwall 17, these studs having reduced diameter threaded portionsreceivable through openings in cars 29 formed on the burner housing. Theclosure plate 20 has openings that receive the studs 28, the shouldersprovided by the large diameter portions of the studs bearing against theclosure plate to hold the latter against the open face of the burner.Other screws (not shown) extend through the closure plate and into theburner housing to hold the closure plate in place.

Extending from the air receiving chamber 10 and into and through the airtube 16 is a fuel conduit and ignition electrode assembly which carriesthe fuel to the burner nozzle (not shown) and which energizes theelectric ignition. This assembly includes a bracket 30 secured as bybolt 31 in the bottom of the partition wall 9 defining the air chamber10. The bracket supports a tube 32, that leads to the nozzle, andinsulated electrodes 33, that extend to an ignition point adjacent thenozzle. Energiza tion of the ignition electrodes is through or by meansof a transformer 35 hinged to the housing wall 1 for swinging movementabout a vertical axis across an opening 36 in such wall. The secondaryof the transformer is connected to terminals 37 which make electricalconnection with spring contacts on the electrodes 33 when thetransformer is in closed position across the wall opening 36. Theprimary of the transformer is connected by an insulated two-wire cable38 to the controls of the heating system, connection being made in awiring box 40 comprising that part of the interior of the housingbetween the partitions and the side walls 4 and 6. The wiringconnections to the electric motor 23 are also made in the wiring chamber40, a two-wire cable 41 from the motor entering the chamber 40 throughan aperture in the main wall 1 of the burner housing.

In the operation of the burner, rotation of the fan 19 produces arotating mass of air in the fan chamber 8, this air dischargingcentrifugally from the fan chamber at the point 15 through the openinginto the connecting passage 12. Replacement air enters the fan chamberthrough the central circular opening 21 along the rotational axis of thefan and moves radially outwardly through the blades of the fan into thetapering passage portion lying between the fan periphery and the Wallsof the chamber 8, the fan and chamber thus constituting the conventionalfan scroll arrangement.

At the bottom of the connecting passage 12 the curved portion 3 of thehousing side wall deflects the air to enter the receiving chamber 10tangentially so as to rotate in the latter in the same direction andsubstantially in the same plane as the mass of air rotates in the fanchamber 8. From the receiving chamber 10 the rotating air advances as aspiral column through the air tube 16, the air tube being a continuationof the receiving chamber 10. Oil or other fluid fuel is supplied to thespirally advancing air column at the end of the air tube 16 or at theend of an extension or head on such air tube and the resulting mixtureis ignited to burn in accordance with well known principles.

Control of the flow of air from the fan chamber 8 through the connectingpassage 12 and into the receiving chamber 10 is effected by a swingablegate 45 with which the present invention is concerned. This gate is madeof sheet metal as by stamping and is suspended from a pivot pin 46aflixed to the top edge of the gate for movement in an arc across theconnecting chamber 12 from the full line position shown in Fig. l to thebroken line position of that figure in which the lower end of the gateengages the connecting wall 11, the latter thus constituting a limitingstop for the gate. The upright side wall of the burner housing is offsetlaterally from the plane of tangency between the housing top curved wall2 and the housing lower curved side wall 3 as by short connecting walls47 and 48 in the provision in the burner housing of a side recess 50which opens into and is continuous with the connecting passage 12. Thepivot pin 46 is located in the recess 50 so that in its full openposition (full lines of Fig. 1) the gate 45 lies substantially in theplane of tangency between the curved wall portions 2 and 3 of thehousing. The gate thus constitutes, in its full open position, a smoothsurfaced tangential guide for air moving between the fan chamber 8 andthe receiving chamber 10 so that a nonturbulent streamline flow may beobtained. In all positions to which it may be adjusted the air gate iswholly outside the air receiving chamber 10 in the lower part of thehousing and does not interfere with the helical or spiral flow of air insuch chamber.

The pivot pin 46 is a square sectioned bar having one end turned down inthe provision of a circular sectioned rod portion 55 supported to turnin a bore drilled through an enlargement or boss 51 formed integrallywith the main wall 1 of the housing and projecting from the plane of thewall into the recess 50. The boss 51 desirably fills the angle betweenthe main wall 1 and the short connecting wall 47 and is integral withthe latter and also with the upright side wall 5. The upper end portionof the gate is disposed flatwise against one of the flat sides of thepivot pin, the latter being supported by the boss 51 in cantileverfashion. The gate is suitably secured to the projecting cantileverportion of the pivot pin as by drive screws 52. It is feasible, ofcourse, for the gate to swing freely on the pivot pin under control of asuitable actuator, but it is preferable, as shown, to employ the pivotpin as an actuator.

One corner of the rectangular plan form gate is relieved or cut away, asshown in Fig. 4, to provide a notch-like opening 54, the notch openingbeing larger than the boss 51 to permit a minimum flow of the airdischarged tangentially from the outer periphery of the fan chamber 8 toby-pass the gate in all positions of the latter.

The circular sectioned rod portion 55 of the pivot pin projects throughthe housing wall 1 and is threaded to receive a nut 43 and an adjustingknob 60. A pointer arm 62 has an apertured hub portion received over theprojecting portion of the pivot rod 55, the pointer being grippedbetween the nut and the knob, preferably with a lock washer 44 alsointerposed. A spring washer 49 received on the projecting portion of thepivot rod 55 between the lock nut 43 and the outside face of the housing1 is compressed in assembly and reacts to draw shoulder 56 of the pivotpin 46 against the inside face of the journal boss 51. This springwasher thus imposes a frictional restraint to turning of the air gaterelative to the boss 51 to maintain the gate in different positions ofadjustment to which it may be shifted.

Within the bore hole in the boss the portion 55 of the pivot pin isengaged by the inner end of a piston-like cylindrical clamping element57 slidable axially in a threaded bore hole which intersects radiallythe bore in which the pivot pin is journaled. Recessed set screw 58 isreceived in the threaded radial bore to exert axial pressure on theclamping element 57 and force the latter against the portion 55 of thepivot pin.

In adjusting the air control the set screw 58 is backed off to relievethe pivot rod portion 55 of clamping pressure so that the latter may beturned in adjusting the air flow as by the knob 60 which, as mentionedabove, is secured on the end of the rod which projects cantileverfashion through the main housing wall 1. The pointer 62 swings acrossthe face of a scale inscribed or embossed on the outside surface of thehousing wall 1 and constitutes an indicator which shows the relativeposition of the air gate in the passage 12. After adjustment of theburner has been effected, the turning of the air gate 45 to differentpositions being under the frictional restraint imposed by the springwasher 49, the set screw 58 is tightened so that the clamping element 57is made to bear radially or in endwise relation against the pivot rod toprevent turning of the latter and to thereby lock the air control gatein adjusted position. Engagement of the cylindrical surface of the rodportion 55 by the flat end face of the clamping element 57 not onlydistributes the pressure along an axially extending line of contactbetween the parts but also permits slight offsetting of the axis of theset screw bore with respect to the desired intersection with the axis ofthe journal bore for the pivot rod 55. It is difficult and costly toobtain perfect location of the bore holes so that their axes intersect.Yet when one axis is offset with respect to the other an objectionableturning of the air gate support rod is likely to result from the use ofconventional set screw arrangements. The interposed piston-like clampingelement of the present invention eliminates such disturbance of the airgate setting upon tightening of the locking set screw. Turning of theset screw is effected as by a screw driver received in its slotted outerend.

In the adjustment of the gate 45 to obtain different air flow conditionsbottom edge 64 of the gate moves to different positions across theconnecting passage 12 so that air being forced through the connectingpassage and into the air receiving chamber 10 in the bottom portion ofthe burner housing is deflected various amounts by the air gate. The airgate thus regulates not only the rate of air flow from the fan chamberinto the receiving chamber 10 but also the direction of the flowing air.While it is highly desirable that air be introduced tangentially intothe receiving chamber 10, it has been found beneficial at some fuelburning rates to introduce some of the air radially or with strongradial components which avoids low pressure effects in the center of theair column and the air mass discharged from the air tube or the burnerhead on the latter and minimizes the tendency of the flame to be drawnback toward the fuel nozzle with attendant burning of the nozzle.

By the arrangement of the air control system of the present invention,in which the air control gate swings on a pivot about an axis at theouter periphery of the path of air discharged tangentially from the fanchamber, the axis being normal to the plane of rotation of the air massin the fan chamber, there is a beneficial shifting of the line of entryof air flowing into the receiving chamber. It is essential, however,that a fractional portion of the air enter the receiving chambertangentially. The open ing 54 in that part of the air control gatelocated adjacent the side wall of the housing and at or relatively closeto the pivot axis of the gate provides a passage for part of the airtangentially discharged from the fan chamber to flow through theconnecting passage 12 without substantial obstruction and tangentiallyto enter the receiving chamber under the guidance of the curved lowerwall portion 3 of the housing. The gate opening 54 extends approximatclyhalf way across the gate width and be tween about one-fifth totwo-fifths, here about one-third, of the gate length. The exactdimensions of the opening 54 are not critical, since the beneficialeffects of the combined tangential and radial entrance of air into thereceiving chamber 10 are obtained with proportions other than indicated.For eifective results, however, the bypass opening 54 should be fromabout 10% to about 25% of the total air gate area. The area of thecut-out is sutficiently large so that with the air gate at its limit ofmovement across the connecting passage, the cut-out passes enough air tomaintain combustion at the minimum oil or fuel rate for which the burneris designed. The opening 54 may be located with some beneficial elfectat any point across the width of the air gate, although its location. asshown, adjacent the rear Wall 1 of the housing and remote from the airtube 16 insures that the portion of the air which enters the receivingchamber tangentially does so closely adjacent the rear wall 1, and thespiraling action of the air thus extends or prevails through the fulllength of the air receiving chamber.

It is thus apparent that the present invention provides an air controlsystem wherein a swingable control gate varies the direction of flow ofmost of the air entering the receiving chamber of the housing While yetmaintaining tangential entrance of a predetermined minimum frac tionalportion of the air to induce the desired spiral How to the air mass inthe air receiving chamber. The structural arrangement of the present airgate permits easy adjustment of the air flow from outside the burnerhousing while the burner is in operation. Provision is made forfrictional restraint on the swinging movements of the air gate so thatthe latter readily may be shifted to and held in any desired position ofadjustment during the burner adjusting operation and can thereafter belocked or clamped in adjusted position.

In accordance with the patent statutes the principles of the presentinvention may be utilized in various ways, numerous modifications andalterations being contemplated, substitution of parts and changes inconstruction being resorted to as desired, it being understood that theembodiment shown in the drawings and described above and the particularmethod set forth are given merely for purposes of explanation andillustration without intending to limit the scope of the claims to thespecific details disclosed.

What I claim and desire to secure by Letters Patent of the United Statesis:

I, In a fluid burner. a housing comprising a substantial y fiat mainwall and a plurality of outer and partition walls substantially normalto the main wall. said walls being arranged to define fan scroll and airreceiving chamhers and a passage connecting the chambers. a bossintegral with the main wall and located adjacent the con necting passageand one of the outer walls. a pivot pin supported by the boss. and anair control gate mounted on the pivot pin for swinging movement todiiferent passage adjusting positions, the gate having top and bottomedges. the gate being mounted on the pivot pin at the top edge, the gatebeing formed with a cutout to accommodate the boss and to provide anopening through the gate adjacent the pivot axis of the latter for theflow of air moving in the passage from the fan chamber to the receivingchamber, the cut-out being adjacent the main wall and adjacent the pivotpin and being located between the pivot pin and the bottom edge of thegate, whereby in all positions of adjustment of the gate in varying theeffective area of the connecting passage the cutout provides. a minimumopening for air traveling a path along said one outer wall.

2. In a fluid fuel burner, 21 housing comprising a substantially flatmain wall and a plurality of outer and partition wall portionssubstantially normal to the main wall, said wall portions being arrangedto define fan scroll and air receiving chambers and a passage connectingthe chambers, a boss integral with the main wall and located adjacentthe connecting passage, a pivot pin comprising a circular sectionedportion journalled in the boss and a non-circular sectioned portionprojecting from the boss cantilever fashion into the interior of thehousing, the circular sectioned portion projecting through the main wallto the housing exterior, an air control gate having top and bottomedges, the top edge being afiixed to the noncircular portion of the pinfor swinging movement to different passage adjusting positions, means onthe portion of the pin which projects through the main wall for manuallyshifting the gate to different positions of adjustment, the pin beingformed with a shoulder at the juncture of the circular and non-circularportions, and resilient means biasing the pin axially outwardly to holdthe shoulder against the boss in the provision of frictional restraintagainst turning of the pin, the housing main wall being between theshoulder and the resilient means.

3. In a fluid fuel burner of the type comprising air pump housing meansdefining a fan chamber, an air receiving chamber of generally circularsection and a passage connecting the chambers for conducting air fromthe fan chamber to the receiving chamber, an air tube having an interiorchamber of generally circular cross section continuous with and disposedas a coaxial extension of the air receiving chamber, said passage beingconnected to the air receiving chamber through an opening into one sideof the latter and being disposed normally to discharge air received fromthe fan chamber substantially tangentially into the receiving chamberwhereby such discharged air rotates in the receiving chamber andadvances as a column through the air tube while rotating spirally aboutthe axis of the receiving chamber and the air tube; the combination of agate and means mounting the gate for swinging movement in the connectingpassage about an axis substantially parallel to the air chamber and tubeaxis about which the advancing air column rotates for intercepting airfrom the fan chamber and adjusting the rate of air flow into thereceiving chamher, the gate having one end substantially at the pivotaxis, the gate extending from the pivot axis in the general direction ofair flow moving through the connecting passage from the fan chamber tothe receiving chamber and having another end which moves in an arcduring swinging movement of the gate between a high rate position inwhich the opening into the air receiving chamber from the connectingpassage is substantially unobstructed by the gate and the air isdischarged into the receiving chamber primarily tangentially, and a lowrate position in which such opening is substantially closed by the gate,and said other end of the gate moving toward the plane defined by theparallel pivot and air tube axes in such swinging movement from high tolow rate positions, whereby in adjusting the gate from said high ratepri marily tangential flow position toward the low rate position the airintercepted by the gate is deflected with a progressively greatercomponent being discharged radially into the receiving chamber toincrease turbulence and decrease spiral rotation of the air column.

4. In an oil burner having a housing providing a fan chamber, a chamberfor receiving air from the fan chamber and a passage so connecting thechambers that air discharged from the periphery of a mass of airrotating in the fan chamber flows substantially tangentially therefromthrough the connecting passage and substantially tangentially into thereceiving chamber, the improvement which comprises a gate mounted on thehousing and movable to different adjusted positions across theconnecting passage to control the flow of air through the latter, saidgate being formed with an opening substantially in the path of theoutermost portion of air discharged peripherally from the fan chamber,said gate opening being of substantially the same area in all positionsof adjustment of the gate, whereby in movement of the gate fromrelatively open to relatively closed positions the effective area of thesaid gate opening is undiminished and as the gate is progressivelyclosed a predetermined minimum and undiminishing portion of theoutermost peripherally discharged air passes through the gate opening toenter the receiving chamber tangentially.

5. In an oil burner having a housing providing a fan chamber, a chamberfor receiving air from the fan chamber and a passage so connecting thechambers that air discharged from the periphery of a mass of airrotating in the fan chamber flows substantially tangentially therefromthrough the connecting passage and substantially tangentially into thereceiving chamber, an air control gate, and means mounting the gate forswinging movement to difierent passage adjusting positions about an axissubstantially at the outer periphery of such rotating air mass, saidgate being formed with an opening substantially in the path of theoutermost portion of air discharged peripherally from the fan chamber,the gate having an edge spaced from its swing axis and which describesan arc during such adjusting movement, said gate opening including aportion located intermediate such edge of the gate and said swing axisand closely adjacent the latter, and said gate opening being ofsubstantially the same area in all positions of adjustment of the gate,whereby in the movement of the gate from relatively open to relativelyclosed positions the effective area of the said gate opening isundiminished and as the gate is progressively closed a predeterminedminimum and undiminishing portion of the outermost peripherallydischarged air passes through the gate opening to enter the receivingchamber tangentially.

6. In a fluid fuel burner, a housing comprising a substantially flatmain wall and a plurality of outer and partition wall portionssubstantially normal to the main wall, said wall portions being arrangedto define fan scroll and air receiving chambers and a passage connectingthe chambers, a boss integral with the main wall and located adjacentthe connecting passage, a pivot pin supported by the boss, and an aircontrol gate mounted on the pivot pin for swinging movement to differentpassage adjusting positions, the gate being formed with a cut out toaccommodate the boss and to provide in all positions of adjustment aminimum opening through the gate adjacent the pivot axis of the latterfor the flow of air moving in the passage from the fan chamber to thereceiving chamber.

7. In a fiuid fuel burner, a housing comprising a substantially flatmain wall and a plurality of outer and partition wall portionssubstantially normal to the main wall, said wall portions being arrangedto define fan scroll and air receiving chambers and a passage connectingthe chambers, a boss integral with the main wall and located adjacentthe connecting passage, a pivot pin journaled in the boss and projectingthrough the main wall, an air control gate mounted on the pivot pin forswinging movement to different passage adjusting positions, the gatebeing formed with a cut out to accommodate the boss and to provide inall positions of adjustment a minimum opening through the gate adjacentthe pivot axis of the latter for the flow of air moving in the passagefrom the fan chamber to the receiving chamber, and means havingconnection with the projecting portion of the pivot pin for shifting thegate to different positions of adjustment.

8. In a fluid fuel burner, a housing comprising a substantially fiatmain wall and a plurality of outer and partition wall portionssubstantiaily normal to the main wall,

said wall portions being arranged to define fan scroll and air receivingchambers and a passage connecting the chambers, a boss integral with themain wall and located adjacent the connecting passage, a pivot pinjournaled in the boss and having cantilever portions projecting one intothe interior of the housing and another through the main wall to thehousing exterior, an air control gate mounted on the one cantileverportion of the pin for swinging movement to different passage adjustingpositions, the gate being formed with a cut out to accommodate the bossand to provide in all positions of adjustment a minimum opening throughthe gate adjacent the pivot axis of the latter for the flow of airmoving in the passage from the fan chamber to the receiving chamber, andmeans secured on the other cantilever portion of the pin exterior to thehousing for turning the pin in shifting the gate to different positionsof adjustment.

9. In a fluid fuel burner, a housing comprising a substantially fiatmain wall and a plurality of outer and partition wall portionssubstantially normal to the main wall, said wall portions being arrangedto define fan scroll and air receiving chambers and a passage connectingthe chambers, a boss integral with the main wall and located adjacentthe connecting passage, a pivot pin comprising a circular sectionedportion journalled in the boss and a non-circular sectioned portionprojecting from the boss cantilever fashion into the interior of thehousing, the circular sectioned portion projecting through the main wallto the housing exterior, an air control gate having top and bottomedges, the top edge being mounted on the non-circular portion of the pinfor swinging movement to different passage adjusting positions, means onthe portion of the pin which projects through the main wall for manuallyshifting the gate to different positions of adjustment, the pin beingformed with a shoulder at the juncture of the portions, and resilientmeans biasing the pin to hold the shoulder against the boss in theprovision of frictional restraint against turning of the pin.

10. In a fluid fuel burner, a housing comprising a substantially fiatmain wall and a plurality of outer and partition wall portionssubstantially normal to the main wall. said wall portions being arrangedto define fan scroll and air receiving chambers and a passage connectingthe chambers, a boss integral with the main wall and located adjacentthe connecting passage, said boss being formed with intersecting journaland set screw bores, a pivot pin journalled in said journal bore, an aircontrol gate having top and bottom edges, the top edge being mounted onthe pivot pin for swinging movement to different passage adjustingpositions, a cylindrical clamping element disposed in the set screw boreand formed on one end with a substantially flat surface arranged to bearagainst the pivot pin, and a set screw threadedly received in the setscrew bore and arranged to bear against the other end of the clampingelement to force the latter against the pivot pin and thereby to clampthe latter in adjusted position, the set screw being rotatableindependently of the clamping element.

11. In a fluid fuel burner of the type comprising air pump housing meansdefining a fan chamber, an air receiving chamber of generally circularsection and a passage connecting the chambers for conducting air fromthe fan chamber to the receiving chamber, an air tube having an interiorcontinuous with and disposed as a coaxial extension of the air receivingchamber, said passage being connected to the air receiving chamberthrough an opening into one side of the latter and being disposednormally to discharge air received from the fan chamber substantiallytangentially into the receiving chamber whereby such discharged airrotates in the receiving chamber and advances as a column through theair tube while rotating spirally about the axis of the receiving chamberand the air tube; the combination of a gate and means mounting the gatefor swinging movement in the connecting passage about an axissubstantially parallel to the air cham' 11 her and tube axis forintercepting air from the fan chamher and adjusting the rate of air flowinto the receiving chamber, the gate having one end substantially at thepivot axis, the gate extending from the pivot axis in the generaldirection of air flow moving through the connecting passage from the fanchamber to the receiving ch2|mher and having another end which moves inan arc during swinging movement of the gate between a high rate positionin which the opening into the air receiving chamber from the connectingpassage is substantially unobstructed by the gate and the air isdischarged into the receiving chamber primarily tangentially, and a lowrate position in which such opening is substantially closed by the gate,said other end of the gate moving toward the plane defined by theparallel pivot and air tube axes in such swinging movement from high tolow rate positions. whereby in adjusting the gate from said high rateprimarily tangential flow position toward the low rate position the airintercepted by the gate is deflected with a progressively greatercomponent being discharged radially into the receiving chamber toincrease turbulence and decrease spiral rotation of the air column, andthe gate being formed with a cutout at said one end adjacent the pivotaxis through which a predetermined and undiminished proportion of theair received from the fan chamber lay-passes the air gate and enters thereceiving chamber tangentially when the gate is being adjusted to and isat the low rate position.

References Cited in the file of this patent UNITED STATES PATENTS787,039 Harris Apr. ll, 1905 960,815 Carlisle June 7, 1910 2,075,587Mesinger Mar. 30. 1937 2,215,281 Von Haase Sept. 17, 1940 2,236,865Bailey et al Apr. l94| 2,478,457 Camerino et a1 Aug. 9, 1949 2,599,153Beckett June 3, 1952 2,645,411 Andler July 14, 1953 FOREIGN PATENTS20,848 France Apr. 24v 1858

